Nucleolar localization of murine nuclear DNA helicase II (RNA helicase A).
Nucleolar localization of murine nuclear DNA helicase II (RNA helicase A).
复制标题
鼠核 DNA 解旋酶 II（RNA 解旋酶 A）的核仁定位。
作者：
Suisheng Zhang;C. Herrmann;F. Grosse
核DNA解旋酶II(NDH II)是真核解旋酶DEXH超家族中高度保守的成员，其生理功能尚不清楚。为了探索NDH II的功能，我们用免疫荧光法研究了不同哺乳动物的NDH II在细胞内的分布，并将这些发现与果蝇同源基因MLE的已知作用进行了比较，MLE参与了性别特异性基因剂量补偿。NDH II在小鼠细胞中显示出明显的核仁定位，而在迄今所研究的所有其他哺乳动物的细胞中，该蛋白仅局限于核质，显然被排除在核仁之外。小鼠NDH II的核仁定位强烈提示其在核糖体RNA生物合成中的作用。免疫电子显微镜研究表明，小鼠NDH II位于核仁的致密纤维成分，并且相当大比例的NDH II分子与RNA聚合酶I(Pol I)转录因子UBF(上游结合因子)共存。此外，NDH II的核仁定位与BrUMP对新生转录物(BrUMP)的优先免疫标记模式一致。此外，小鼠NDH II在有丝分裂中的重新分布与Pol I的活性高度相关。在间期抑制Pol I活性的条件减少了扩散到核质和胞质中的核仁中NDH II的数量。与抑制rRNA合成的效果相反，翻译抑制剂放线菌酮处理小鼠细胞并不影响小鼠NDH II的核仁定位。
Nuclear DNA helicase II (NDH II) is a highly conserved member of the DEXH superfamily of eukaryotic helicases, whose physiological role is still unclear. To explore the function of NDH II, we studied the intracellular distribution of NDH II of different mammalian species by immunofluorescence and compared these findings with the known role of the Drosophila homologue MLE that is involved in sex-specific gene dosage compensation. NDH II displayed an apparent nucleolar localization in murine cells, whereas in cells from all other mammalian species examined so far the protein was confined to the nucleoplasm and apparently excluded from the nucleoli. The nucleolar localization of mouse NDH II strongly suggests a role in ribosomal RNA biosynthesis. Immunoelectron microscopic studies revealed that the mouse NDH II was found at the dense fibrillar components of the nucleoli, and a significant percentage of NDH II molecules colocalized with the RNA polymerase I (Pol I) transcription factor UBF (upstream binding factor). Additionally, the nucleolar localization of NDH II coincided with a preferential immunolabeling pattern of nascent transcripts with bromouridine (BrUMP). Furthermore, mouse NDH II redistributed in mitosis in a manner highly correlated with Pol I activity. Conditions leading to the inhibition of Pol I activity in the interphase decreased the amount of NDH II in the nucleoli that diffused into the nucleoplasm and the cytosol. Contrary to the effect of inhibiting rRNA synthesis, treatment of mouse cells with the translation inhibitor cycloheximide did not compromise the nucleolar localization of murine NDH II.
影响因子：
56.9
作者：
H. Tang;G. Gaietta;W. Fischer;Mark Ellisman;F. Wong-Staal
通讯作者：
H. Tang;G. Gaietta;W. Fischer;Mark Ellisman;F. Wong-Staal